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Properties, Mechanisms, Benefits, Safety, Comparison, Regulations, Future Developments of Zinc Oxide in Sunscreens

Last updated: Aug 2023
In this article:

Properties of Zinc Oxide

Physical Properties:

  • Appearance: Zinc oxide is a white, powdery solid that is often found in the form of fine particles or crystals. It has a hexagonal crystal structure.
  • Melting Point: The melting point of zinc oxide is relatively high, around 1,975 degrees Celsius (3,587 degrees Fahrenheit).
  • Density: Zinc oxide has a density of approximately 5.61 grams per cubic centimeter. This density contributes to its characteristic heaviness.
  • Solubility: While zinc oxide is insoluble in water, it can dissolve in acids and alkaline solutions.
  • Optical Properties: Zinc oxide is transparent in the ultraviolet (UV) region but becomes opaque in the visible and infrared regions. This unique property makes it useful in various optical applications, such as sunscreen and optical filters.
  • Electrical Conductivity: Pure zinc oxide is considered an insulator. However, when doped with certain impurities, it exhibits semiconducting properties.

Chemical Properties:

  • Reactivity: Zinc oxide is chemically stable and does not react with oxygen under normal conditions. However, it can react with acids and bases to form various zinc salts.
  • Photocatalytic Activity: Zinc oxide exhibits photocatalytic properties, meaning it can accelerate chemical reactions in the presence of light. This property finds applications in wastewater treatment and air purification.
  • Antimicrobial Properties: Zinc oxide possesses antimicrobial properties, making it effective against a broad spectrum of bacteria and fungi. This property is utilized in various products, including antibacterial ointments and skin creams.
  • UV Absorption: Zinc oxide is an effective UV absorber, which makes it a common ingredient in sunscreens. It absorbs both UVA and UVB rays, protecting the skin from harmful radiation.
  • Thermal Stability: Zinc oxide is highly stable at elevated temperatures, making it useful in heat-resistant coatings, ceramics, and rubber products.

Understanding the physical and chemical properties of zinc oxide is crucial for harnessing its potential in numerous industrial and commercial applications. Whether it is in the fields of optics, medicine, or environmental protection, the unique characteristics of zinc oxide make it a valuable compound with a diverse range of applications.

UV Protection: Mechanisms of Action

Physical Protection:

UV radiation from the sun can be harmful to the skin, leading to sunburns, premature aging, and an increased risk of skin cancer. Understanding how UV protection works can help us choose the right products and take appropriate measures to protect our skin.

  • Physical protection involves the use of sunscreens that create a physical barrier between the skin and UV rays.
  • These sunscreens contain ingredients like titanium dioxide or zinc oxide, which reflect and scatter UV radiation away from the skin.

Chemical Protection:

  • Chemical protection involves the use of sunscreens that contain organic compounds like avobenzone or octinoxate.
  • These compounds absorb UV radiation and convert it into heat, reducing its harmful effects on the skin.
  • Chemical sunscreens are often more convenient to use as they are easier to apply, but they may cause skin irritation or allergies in some individuals.

Antimicrobial Effects: Mechanisms of Action

Disruption of Cell Membrane:

Microorganisms, such as bacteria and fungi, can cause various infections and diseases. Understanding the mechanisms by which certain substances possess antimicrobial effects can help us make informed choices when it comes to hygiene and medical treatments.

  • Some antimicrobial substances disrupt the cell membrane or wall of microorganisms.
  • This can lead to leakage of essential cellular components, cell lysis, and eventually the death of the microorganism.

Inhibition of Essential Enzymes or Processes:

  • Antimicrobial substances can inhibit essential enzymes or processes in microorganisms.
  • By targeting specific enzymes or processes necessary for microbial survival, growth, or replication, antimicrobial substances can interfere with their normal functioning and inhibit their growth or kill them.

Disruption of Genetic Material:

  • Antimicrobial substances can disrupt the genetic material of microorganisms.
  • This can weaken the microorganism's ability to survive and reproduce, ultimately causing their death.

Anti-inflammatory Effects: Mechanisms of Action

Inhibition of Pro-inflammatory Molecules:

Inflammation is a natural response of the body to injury or infection. However, chronic or excessive inflammation can lead to various health issues. Understanding the mechanisms of anti-inflammatory substances can help us manage inflammation and potentially alleviate symptoms associated with inflammatory conditions.

  • Some anti-inflammatory substances inhibit the production of pro-inflammatory molecules, such as cytokines or prostaglandins.
  • By blocking the production or activity of these molecules, the inflammatory response can be dampened, reducing inflammation and associated symptoms.

Suppression of Inflammatory Immune Cells:

  • Other anti-inflammatory substances suppress the activity of immune cells involved in the inflammatory response, such as macrophages or neutrophils.
  • By targeting these cells and reducing their activation or inflammatory response, anti-inflammatory substances can mitigate inflammation.

Antioxidant Properties:

  • Some anti-inflammatory substances also possess antioxidant properties.
  • Oxidative stress can contribute to inflammation and tissue damage.
  • Anti-inflammatory substances with antioxidant effects can neutralize free radicals and reduce oxidative stress, thereby decreasing inflammation.

Sunscreen Formulation

Sunscreen is an essential part of our daily skincare routine to protect our skin from harmful UV rays. It acts as a barrier between our skin and the sun, preventing sunburns and reducing the risk of skin cancer. To create an effective sunscreen formulation, several key ingredients are necessary.

  • UV filters like zinc oxide or titanium dioxide that block harmful UVB and UVA rays
  • Emollients like coconut oil or shea butter to keep the skin moisturized and prevent dryness

It is essential to choose a sunscreen with a broad-spectrum formula to ensure protection against both UVA and UVB rays.

Acne Treatment

Acne is a common skin condition that affects many people worldwide. One effective way to treat and prevent acne is by using topical treatments. These treatments usually contain active ingredients like benzoyl peroxide or salicylic acid.

  • Benzoyl peroxide works by killing bacteria on the skin surface, which contributes to acne formation
  • Salicylic acid helps to unclog pores and reduce inflammation

When choosing an acne treatment, it's important to consider your skin type and the severity of your acne. It is advised to consult with a dermatologist for personalized advice.

Wound Healing

Proper wound healing is crucial to minimize scarring and reduce the risk of infection. One important factor in promoting wound healing is keeping the wound clean and moist. Using an antiseptic solution or gentle soap and water can help prevent infection.

After cleaning the wound, applying a suitable wound dressing can aid the healing process. Common choices include hydrocolloid dressings, which absorb excess fluid and create a moist environment for the wound to heal. Changing the dressing regularly and following proper hygiene practices will accelerate the healing process.

Diaper Rash Treatment

Diaper rash is a common issue among infants and can cause discomfort and irritation. To treat diaper rash effectively, frequent diaper changes and keeping the area clean are crucial. Avoid using baby wipes that contain alcohol or fragrance, as these can exacerbate the rash. Instead, opt for gentle cleansing wipes or rinse the area with warm water.

Applying a diaper rash cream containing zinc oxide or petroleum jelly can create a protective barrier and soothe the affected skin. Letting the baby go diaper-free for short periods can also help in healing the rash by allowing the skin to breathe.

Skin Irritation

Skin irritation is a common concern for many individuals, especially when using certain personal care products or coming into contact with allergens. To minimize the risk of skin irritation:

  • Read product labels carefully, paying attention to any allergens or irritants listed.
  • Conduct a patch test before using a new product, especially if you have sensitive skin.
  • Avoid overuse of harsh products, such as exfoliants or strong cleansers, as they can strip the skin's natural barrier.
  • Moisturize regularly to maintain skin hydration and prevent dryness, which can lead to irritation.
  • If you experience persistent skin irritation, consult a dermatologist for further evaluation and advice.


Understanding the potential toxicity of substances is crucial for personal safety and the environment. Consider the following steps:

  • Educate yourself about the potential risks associated with certain chemicals, such as those commonly found in cleaning products or pesticides.
  • Follow proper safety guidelines when handling potentially toxic substances, including wearing protective gear like gloves and masks.
  • Store hazardous products in a secure location, out of reach of children and pets.
  • Dispose of hazardous waste appropriately, following local regulations and guidelines provided by your municipality.

Environmental Impact

Many products and substances can have adverse effects on the environment, such as pollution or harm to wildlife. Do your part to minimize environmental impact:

  • Opt for eco-friendly alternatives whenever possible, such as biodegradable cleaning products or organic pesticides.
  • Reduce, reuse, and recycle to minimize waste and prevent pollution.
  • Properly dispose of electronic waste, batteries, and other hazardous materials at designated collection points.
  • Support companies and brands that prioritize sustainability and environmentally-friendly practices.


Maintaining safety and minimizing side effects requires awareness and proactive measures. By following these guidelines, you can protect yourself, others, and the environment from potential harm and contribute to a safer and healthier world.

Comparison to Other Sunscreen Ingredients

Chemical sunscreens:

  • Chemical sunscreens provide broad-spectrum protection against UVA and UVB rays by absorbing the sun's rays and converting them into heat, which is then released from the skin.
  • They have a lightweight and non-greasy texture, making them suitable for daily use. They come in various forms such as lotions, creams, gels, and sprays.
  • However, certain chemicals used in sunscreens, like oxybenzone and octinoxate, are raising concerns about their environmental impact on coral reefs. It is recommended to choose reef-safe options that do not contain these harmful ingredients.

Titanium dioxide:

  • Titanium dioxide is a mineral sunscreen ingredient that forms a physical barrier on the skin, reflecting and scattering the sun's rays to provide UVA and UVB protection.
  • It is suitable for sensitive skin as it is generally non-irritating and less likely to cause allergic reactions compared to chemical sunscreens.
  • Titanium dioxide is photostable, meaning it does not degrade or lose its effectiveness when exposed to sunlight.
  • However, it can leave a white or chalky residue on the skin. Many sunscreen manufacturers now use micronized or nano-sized particles to minimize the white cast effect.
  • High-quality titanium dioxide particles undergo rigorous testing for safety and efficacy. Look for "broad-spectrum" labeled products to ensure comprehensive protection against UVA and UVB rays.


Chemical sunscreens offer lightweight and versatile options, but their potential environmental impact and sensitivity concerns may lead individuals to choose titanium dioxide-based sunscreens. The decision between these two types of sunscreen ingredients should be based on personal preferences, skin type, and environmental considerations.

FDA Regulations

Product Registration

  • FDA regulations require manufacturers to register their establishments and submit product-specific information. This includes ingredients, labeling, and manufacturing processes. By registering their products, manufacturers demonstrate compliance and provide consumers with transparency.

  • Good Manufacturing Practices (GMP)

    To ensure product safety and quality, the FDA mandates adherence to GMP standards. These guidelines cover areas such as facility cleanliness, employee training, quality control, and record-keeping. Following GMP protocols is essential for manufacturers to produce safe and reliable products.

  • Labeling Requirements

    The FDA also regulates product labeling to provide consumers with accurate information. Labels must include the product's name, ingredients, usage directions, warnings, and any potential allergens. Manufacturers must comply with FDA guidelines to prevent misleading claims and ensure consumer safety.

SPF Labeling


  • SPF measures a sunscreen's ability to protect against UVB rays, which are primarily responsible for sunburns. The higher the SPF, the greater the protection. It is important to note that SPF does not measure protection against UVA rays, which can also cause skin damage.

  • Proper Usage

    SPF values indicate the estimated amount of time a person can stay in the sun without getting burned. For instance, if someone typically starts to burn after 10 minutes of unprotected sun exposure, using a sunscreen with SPF 30 would theoretically allow them to stay in the sun for 300 minutes (10 minutes x 30 SPF). However, regular reapplication of sunscreen is crucial for adequate protection.

  • Broad Spectrum

    Look for sunscreens labeled as "broad-spectrum" that protect against both UVA and UVB rays. These offer the most comprehensive sun protection.

  • Water Resistance

    Sunscreens claiming to be water-resistant will specify the duration of their effectiveness—typically either 40 or 80 minutes. Reapplication after swimming or heavy sweating is necessary to maintain protection.

Future Research and Developments

  • Nano-sized Zinc Oxide

Nano-sized zinc oxide (ZnO) has gained significant attention in recent years due to its unique and enhanced properties compared to conventional zinc oxide. As a result, there is a growing interest in conducting further research and development in this area to unlock its full potential.

  • Synthesis and Characterization

One area of future research is focused on the synthesis and characterization of nano-sized ZnO particles. The morphology, size, and crystal structure of these particles play a crucial role in determining their properties and applications. Researchers are exploring various synthesis techniques such as sol-gel, hydrothermal, and chemical vapor deposition methods to fine-tune the size and shape of the particles for specific applications.

  • Investigating Properties

Furthermore, investigating the various properties of nano-sized ZnO is also a crucial aspect of future research. Properties such as optical, electrical, and photocatalytic behavior need to be thoroughly understood to harness the full potential of these particles. Researchers are utilizing advanced characterization techniques like X-ray diffraction, scanning electron microscopy, and UV-visible spectroscopy to obtain detailed insights into these properties.

Combination with Other Ingredients

Another exciting area of future research and development is the combination of nano-sized ZnO with other ingredients to create multifunctional materials with enhanced properties. The combination of ZnO nanoparticles with materials like polymers, metals, and ceramics can lead to the development of novel nanocomposites that possess unique characteristics.

  • Potential of Nanocomposites

One focus of future research is on exploring the potential of these nanocomposites in various applications. For instance, combining ZnO nanoparticles with polymers can result in flexible and transparent materials with improved UV protection and antimicrobial properties. This can find applications in sunscreens, flexible electronics, and medical devices.

  • Synergistic Effects

Furthermore, the synergistic effects between ZnO nanoparticles and other ingredients need to be studied in detail. Researchers aim to understand how the addition of ZnO nanoparticles affects the mechanical, thermal, and electrical properties of the composite materials. This knowledge can aid in designing materials with tailored properties to meet specific industrial and technological requirements.


Zinc Oxide Benefits for Skin

  • Zinc oxide is a popular ingredient in skincare products due to its numerous benefits for the skin.
  • It provides broad-spectrum sun protection by reflecting and scattering UVA and UVB rays, thus preventing sunburn and skin damage.
  • Zinc oxide possesses anti-inflammatory properties and can soothe and calm irritated or inflamed skin, making it beneficial for those with acne or rosacea.
  • It acts as a physical barrier on the skin's surface, protecting it from environmental pollutants, irritants, and bacteria, thus promoting a healthier complexion.
  • Zinc oxide is non-comedogenic, meaning it does not clog pores, making it suitable for all skin types, including sensitive and acne-prone skin.
  • Additionally, it possesses wound-healing properties and may help in reducing the appearance of scars and promoting cellular repair and regeneration.